1. Field of the Invention
The present invention relates generally to web handling, and more particularly to a web cinching and winding apparatus. To cinch the web end portion onto a core, the core is center driven at an outer surface speed greater than the transport speed of the web end portion fed to and threaded around the core. After the web end portion is cinched onto the core and the web wound to form a roll of predetermined diameter, the core center drive is terminated, and substantially simultaneously the outer surface of the roll is surface driven.
2. Description of the Prior Art
U.S. Pat. No. 3,585,779 discloses a winding apparatus in which a web end portion is cinched onto a spool by rotatably driving the spool at an outer surface speed in excess of the speed at which the web end portion is fed to and threaded around the spool. After cinching, the web is wound onto the spool by continued driving of the spool, commonly referred to in the industry as center drive winding.
It is also known in the prior art, of which U.S. Pat. Nos. 3,537,664 and 3,692,252 are exemplary, to initially attach or fasten a web end portion onto a core, and then drive the outer surface of web convolutions on the core by means of a builder roller to form a roll. This means of winding a roll is commonly referred to in the industry as surface winding.
A web cinching device is disclosed in U.S. Pat. No. 3,884,427 wherein web cinching is achieved by an endless belt wrapper. A wrapping mechanism wraps a belt almost completely around the outer periphery of a core leaving a small gap between the belt and core into which a web end portion is fed. After the web end portion is cinched onto the core, the belt is withdrawn.
Copending U.S. patent application Ser. No. 218,592 entitled "Web Cinching and Winding Apparatus and Method" by M. A. Kildal and S. J. Hassall filed on Dec. 19, 1980 describes a web cinching apparatus wherein web cinching and winding of web convolutions is initially achieved by center driving the core at a speed in excess of the web transport speed. After cinching and partial winding is achieved, the center driving of the core is terminated and the web is wound on the roll by surface driving the roll with a builder roller. Center driving of the core at a speed in excess of the web transport speed is achieved by resilient tires mounted on the periphery of the builder roller drivingly engaging cylindrical rims on a core chuck.
The prior art is further replete with speed reducing the increasing apparatus, of which U.S. Pat. No. 3,227,005 is exemplary, in which speed reducing and speed increasing is achieved by way of ball bearings.
One of the problems with winding devices in which the core is solely center driven is adequately controlling winding torque and web tension as the roll diameter increases, particularly where large rolls are wound. This has in instances necessitated the use of complicated and expensive control devices.
In winding devices in which the roll is solely surface driven, the web and core are traveling at the same speed. Since cinching a web end portion on a core can be defined as tightening a web by pulling on the web while holding the core (after the web end portion has entered the nip between the core and first web convolution) relative motion between the web and core is implied. Since relative motion between the web and core is not present in surface winding, cinching as defined above is unobtainable. In order to attach the web end portion to the core, means must be provided such as closely spaced threading guides, rollers or elastic bands surrounding the core to insure intimate contact of the web to the core. Such threading guides present problems, for example, of increased costs and reduced reliability due, among other things, to the precision required in manufacturing the parts, and the close tolerances involved in assembly and operation.
A problem with belt or band wrapping devices is difficulty of adjusting the device which is extremely critical. Improper adjustment of the belt wrapping device can result in web surface abrasion when the belts are around the core, and cinching failures with severe consequences. The belts further have to be replaced periodically.
A problem with web cinching apparatus of the type having tires fixedly mounted on the ends of a builder roller for driving a core chuck and core is that the tires are not axially adjustable on the roller. Such adjustability is necessary to accommodate axially adjustable core chucks for handling cores and slit webs of varying width.